Influence of sulphate ions on the crystal chemistry of white cement mortars with a high content of marble filler powder

The objective of this study was evaluation of the photocatalytic performance of the addition of n-TiO2 in white cement mortars in terms of the light reflection (evaluated by CIE L*a*b* scale) and reflectance of the mortar surfaces exposed to solar radiation in an urban environment. Are produced specimens of 1.2m × 1.2m with n-TiO2 additions of 1%, 5%, and 10% concerning to the total dry powder mass.The performances of the specimens were then compared with two sets without n-TiO2,painted and unpainted, and these were used as references. To conduct an in-situ experiment, the mortars were mixed and applied by a mason. After 41 months of exposure and washing of the specimens, the painted mortars and the mortars with the addition of different n-TiO2 contents exhibited a statistically equivalent reflectance under exposure to solar radiation. All specimens exhibited color differences resulting from: (i)the accumulation of dirt on the surface; (ii) an increase in the surface roughness of the specimens; and (iii)a decrease in rainfall over the duration of exposure.

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Influence of a Retarding Admixture on the Behavior of Mortars Made from Different Types of Cement

International Journal of Engineering & Technology ◽

10.14419/ijet.v7i4.20.26129 ◽

2018 ◽

Vol 7 (4.20) ◽

pp. 334

Author(s):

Tumadhir Merawi Borhan ◽

Munaf A. Al-Ramahee ◽

Noor Al-Hassnawi ◽

Zaid Ali AlZaidi

Keyword(s):

Compressive Strength ◽

Portland Cement ◽

Cement Mortar ◽

Setting Time ◽

Length Change ◽

Setting Times ◽

White Cement ◽

Cement Mortars ◽

Different Types ◽

Positive Effect

The effect of retarding admixture on the fresh and hardened behaviour of different types of cement mortars and pastes when using a retarding admixture was investigated in this study. The types of cement used are; White cement (WhC), Ordinary Portland cement (OPC) and Sulphate Resistant Portland cement (SRC). Different cement mortar and paste mixes were cast, for this purpose, with and without the admixture. Initial and final setting times, compressive strength, length change, absorption and density for these mixes were examined at the curing ages of 3,7,28,45 days. The results showed that the addition of retarding admixture delayed the setting time significantly of WhC paste. The retarding admixture has a positive effect on the compressive strength of the mortar specimens for all types of cement used. regarding the length change test, the admixture was found to reduce the initial expansion for all types of cement at all ages. The results also showed an increase in the density and decrease in water absorption, especially at the later ages for all types of cement. Among all cement types used, WhC was noticeably the most affected type by using the retarding admixture compared to other types of cement used.

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